1. Field of the Invention
The present invention relates to an imaging lens and an imaging apparatus, more particularly, to an imaging lens suitable to be used in a surveillance camera, a cell phone camera, an on-board camera, and the like employing an imaging device such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor), and an imaging apparatus having the imaging lens.
2. Description of Related Art
Recently, imaging devices such as CCD and CMOS have been to a great extent miniaturized and the number of pixels thereof excessively increased. In addition, an imaging apparatus main body having the imaging device has also been miniaturized, and thus it is also required to not only achieve favorable optical performance but also weight reduction and miniaturization of an imaging lens mounted therein.
Known wide-angle imaging lenses with three-lens system include lenses disclosed in JP-A-2001-337268, JP-A-2005-181596, JP-A-2007-133324, JP-A-2008-89813 and JP-A-2008-102500. These documents disclose imaging lenses with three-group, three-lens system having an aspheric surface, in which a negative lens, a positive lens, an aperture diaphragm, and a positive lens are arranged in order from the object side. Further, JP-A-2007-114546 discloses an imaging lens with three-group, three-lens system having an aspheric surface, in which a negative lens, a positive or negative lens, an aperture diaphragm, and a positive lens are arranged in order from the object side.
However, in imaging apparatuses in the above-mentioned field, not only the demands for low cost and high performance but also the demand for further miniaturization has become stronger. Further, recently, in addition to these demands, the demand for wide angle has become stronger too. For example, there is a demand for an imaging lens capable of performing photographing with a wide angle of view greater than 130°.
However, the imaging lenses disclosed in JP-A-2001-337268 and JP-A-2005-181596 are not good in view of miniaturization of the lens system. Further, the imaging lenses disclosed in JP-A-2007-133324, JP-A-2008-89813 and JP-A-2008-102500 have small angles of view, and do not satisfy the recent demand for wide angle. The imaging lens disclosed in JP-A-2008-89813 tends to have a wider angle of view than that disclosed in JP-A-2007-133324. Further, the imaging lenses disclosed in JP-A-2005-181596, JP-A-2008-102500, and JP-A-2007-114546 employ glass as a first lens material. Hence, it is possible to manufacture a lens with high weather resistance, but if further cost reduction is required, there is a room for improvement in that costs increase.